1. Field of the Invention
The present invention relates to a substrate, and in particular relates to a surface-enhanced Raman scattering substrate and a trace detection method of a biological and chemical analyte using the same.
2. Description of the Related Art
There are several poisonous chemical pollutants in the environment, and these pollutants have different maximum allowable concentrations, e.g. benze (5.1 ppb), Pb (50 ppb), Cd (5 ppb), paraquat (20 ppb), 1,1,1-trichloroethane (0.2 ppm). However, traditional detection instruments are expensive and take a lot of time for measurements, thereby limiting its time-effectiveness and popularity. Therefore, those skilled in the art are devoted to develop a highly sensitive, rapid and low cost trace detection device to analyze biological and chemical analytes.
A Raman Scattering Spectrum has the advantages of fingerprint specificity and multi-domain applications, and thus it is applied to trace detection. However, the Raman scattering intensity is very weak. Scientists use a metal structure to induce the surface-Enhanced Raman Scattering (SERS) to amplify the scattering intensity 104-1012 times.
The U.S. Pat. No. 7,242,470 discloses a nanostructure formed on a substrate. The nanostructure in the form of nanosphere is arranged self-assembly on the substrate. However, the adhesion between the nanostructure and the substrate is poor, and the nanostructure is not a continuous film. Thus, fabricating such SERS substrate having a large area, high uniformity and high Raman scattering intensity is a challenge.
The U.S. Pat. No. 7,864,313 discloses a substrate. A photonic crystal structure and a Bragg reflector are formed on the substrate to enhance the Raman scattering intensity of the analytes approaching the substrate. However, the substrate is formed by a photo lithography process, a physical etching process or chemical etching process, and these processes are expensive and time consuming.
Accordingly, there is a need to develop a large area, inexpensive SERS substrate, and the substrate also has a high Raman scattering intensity for trace analysis application.